All things considered, I still feel that Freecell Solver is probably the best quality Solitaire solver out there. While it still has a lot of room for improvement, the rest of its competition have much bigger issues, or have not been made available (yet or ever).
Several factors contributed for its success: the fact that I announced many releases on Freshmeat.net, that I received a lot of input from my users and co-developers, that I was determined to constantly improve it and work on it, and that I worked on creating and maintaining a good web-site and documentation.
While most of the contributions of code I received were limited, the input from the users of the software proved to be crucial for its prosperity. Like I noted earlier, I lost interest in working on it (at least temporarily), but still maintain it, and feel that it is good enough as it is.
I hope this document, and similar resources it referenced will help you in working on your software, and improving its quality for the benefit of your users and you.
Happy Hacking!